Equity (Common Stock - Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Nov. 01, 2017	Nov. 10, 2016	Sep. 22, 2015
Business Acquisition [Line Items]
Common Stock, Shares, Issued	1,168,710,101	1,164,029,985
Cost of shares issued	$ 167	$ 195	$ 182
Stock Repurchase Program, Authorized Amount				$ 2,000	$ 3,000
Class of Stock Disclosures [Abstract]
Repurchase amount outstanding	$ 1,800
Repurchase Shares	56,599,540	6,948,739	39,491,991
Treasury Stock, Value, Acquired, Cost Method	$ 2,927	$ 372	$ 1,930
Common Shares Issued For Stock Options [Member]
Business Acquisition [Line Items]
Common stock, shares issued	4,680,116	4,439,219	5,592,622
Cost of shares issued	$ 158	$ 166	$ 216
Treasury Shares Issued For Stock Options [Member]
Business Acquisition [Line Items]
Issued Treasury Stock	0	0	0
Board Increase Of Repurchase Program [Member]
Business Acquisition [Line Items]
Stock Repurchase Program, Authorized Amount						$ 739